Infant development is strongly affected by the nature and quantity of interactions the infant has with his parents over time. Qualitative aspects of father involvement are improved variables for this development. Specific paternal attitudes and behaviors during the neonatal periods may be particularly crucial to the development of subsequent patterns of interacting in the father-infant dyad, and thus to the infants' behavior and development. This last assumption will serve as a general hypothesis for the proposed studies. The hypothesis will be tested by a longitudinal assessment of fathers' attitudes and expectations about his infant and about his role as a father; by a longitudinal assessment of specific patterns of interaction in the father-infant dyad; and by linking these to assessment of the infants' cognitive and social development. Once the importance of specific factors of early father involvement has been assessed, these factors will be incorporated into training and intervention procedures designed to facilitate fathers' adoption of fathering roles, attitudes, and behaviors that were earlier found to enhance infant development and subsequent patterns of social interaction in the father-mother-infant triad. A transfer-of-training research paradigm will be utilized to assess the effectiveness of these techniques for the modification of relevant fathering behaviors.